N-way broadcast / narrowcast combiner

ABSTRACT

Systems and methods are described for an optiplex. A method includes: conveying a first narrowcast signal to a first optical combiner; conveying a second narrowcast signal to a second optical combiner; tapping into said first narrowcast signal; monitoring a first characteristic of said first narrowcast signal; tapping into said second narrowcast signal; monitoring a second characteristic of said second narrowcast signal; combining a broadcast signal with the first narrowcast signal using the first optical combiner; and combining said broadcast signal with the second narrowcast signal using the second optical combiner. An apparatus includes: a first optical input; an optical splitter connected to said first optical input; a first optical waveguide connected to said optical splitter; a second optical waveguide connected to said optical splitter; a first optical combiner connected to said first optical waveguide; a second optical combiner connected to said second optical waveguide; a second optical input; an optical demultiplexer connected to said second optical input; a third optical waveguide connected to said optical demultiplexer; a fourth optical waveguide connected to said optical demultiplexer; a first tap coupler connected to said third optical waveguide and said first optical combiner; a second tap coupler connected to said forth optical waveguide and said second optical combiner; a first optical signal sensor coupled to both said first tap coupler and a signal processing unit; and a second optical signal sensor coupled to both said second tap coupler and said signal processing unit.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of, and claims a benefit of priorityunder 35 USC 120 from patent application U.S. Ser. No. 09/850,935, filedMay 7, 2001, now U.S. Pat. No. 7,266,298, issued Sep. 4, 2007, theentire contents of which are hereby expressly incorporated herein byreference for all purposes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to the field of communications. Moreparticularly, the invention relates to optical signal routing and/ordistribution. Specifically, a preferred implementation of the inventionrelates to an optical N-way broadcast/narrowcast combiner.

2. Discussion of the Related Art

In the past, when it was necessary to combine broadcast and narrowcastsignals, the passive optical components, for example a demultiplexer, asplitter and a plurality of combiner filters, were all provided inseparate enclosures. These separate enclosures were then allinterconnected by plugging fiber optic jumpers into a fiber managementchassis. One, or more, of the enclosures and/or the chassis might alsorequire a power connection.

A problem with this approach has been that the resulting collection ofequipment requires a large number connections including the opticalfiber jumpers. Another problem with this approach has been that housingthe resulting amalgamation of equipment requires a large volume ofspace. Typically, the enclosures and the chassis are arranged in rack(s)with the connections draped down between the enclosures.

Another disadvantage of this approach has been relatively high cost.While each of the underlying components within each of the enclosuresmay be essential to the operation of the system, each of the enclosuresrepresents an unnecessary expense. The mounting equipment within each ofthe enclosures also represents an additional expense. The fiber opticjumpers are also expensive, as is the rack space to house all of theequipment. Therefore, what is needed is a solution that permits anoptical broadcast/narrowcast system to be provided with fewerconnectors, while occupying less space and in a more cost-effectivemanner.

Heretofore, the requirements of fewer connectors, less space and lowercost referred to above have not been fully met. What is needed is asolution that addresses all of these requirements.

SUMMARY OF THE INVENTION

There is a need for the following embodiments. Of course, the inventionis not limited to these embodiments.

According to a first aspect of the invention, a method comprises:conveying a first narrowcast signal to a first optical combiner;conveying a second narrowcast signal to a second optical combiner;tapping into said first narrowcast signal; monitoring a firstcharacteristic of said first narrowcast signal; tapping into said secondnarrowcast signal; monitoring a second characteristic of said secondnarrowcast signal; combining a broadcast signal with the firstnarrowcast signal using the first optical combiner; and combining saidbroadcast signal with the second narrowcast signal using the secondoptical combiner. According to a second aspect of the invention, anapparatus comprises: a first optical input; an optical splitterconnected to said first optical input; a first optical waveguideconnected to said optical splitter; a second optical waveguide connectedto said optical splitter; a first optical combiner connected to saidfirst optical waveguide; a second optical combiner connected to saidsecond optical waveguide; a second optical input; an opticaldemultiplexer connected to said second optical input; a third opticalwaveguide connected to said optical demultiplexer; a fourth opticalwaveguide connected to said optical demultiplexer; a first tap couplerconnected to said third optical waveguide and said first opticalcombiner; a second tap coupler connected to said forth optical waveguideand said second optical combiner; a first optical signal sensor coupledto both said first tap coupler and a signal processing unit; and asecond optical signal sensor coupled to both said second tap coupler andsaid signal processing unit.

These, and other, embodiments of the invention will be betterappreciated and understood when considered in conjunction with thefollowing description and the accompanying drawings. It should beunderstood, however, that the following description, while indicatingvarious embodiments of the invention and numerous specific detailsthereof, is given by way of illustration and not of limitation. Manysubstitutions, modifications, additions and/or rearrangements may bemade within the scope of the invention without departing from the spiritthereof, and the invention includes all such substitutions,modifications, additions and/or rearrangements.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings accompanying and forming part of this specification areincluded to depict certain aspects of the invention. A clearerconception of the invention, and of the components and operation ofsystems provided with the invention, will become more readily apparentby referring to the exemplary, and therefore nonlimiting, embodimentsillustrated in the drawings, wherein like reference numerals designatethe same elements. The invention may be better understood by referenceto one or more of these drawings in combination with the descriptionpresented herein. It should be noted that the features illustrated inthe drawings are not necessarily drawn to scale.

FIG. 1 illustrates a circuit schematic view of an 8-way optiplex withintegral diagnostics, representing an embodiment of the invention.

FIG. 2 illustrates a circuit schematic view of an 8-way optiplex withintegral diagnostic and optical level control, representing anembodiment of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

The invention and the various features and advantageous details thereofare explained more fully with reference to the nonlimiting embodimentsthat are illustrated in the accompanying drawings and detailed in thefollowing description. Descriptions of well known components andprocessing techniques are omitted so as not to unnecessarily obscure theinvention in detail. It should be understood, however, that the detaileddescription and the specific examples, while indicating preferredembodiments of the invention, are given by way of illustration only andnot by way of limitation. Various substitutions, modifications,additions and/or rearrangements within the spirit and/or scope of theunderlying inventive concept will become apparent to those skilled inthe art from this detailed description.

The context of the invention can include a communications network. Thecontext of the invention can also include optical signal switchingand/or routing and/or distribution. The context of the invention canalso include optical signal combining and/or multiplexing and/ordecombining and/or demultiplexing.

The invention can include an optical N-way broadcast/narrowcastcombiner. Such a combiner can be termed an optiplex.

The invention can include diagnostic functionalities. These diagnosticfunctionalities can be based on, for example, tap couplers and opticalsensors. The diagnostic functionalities can be integrated with thecombiner via associated microprocessor(s).

The invention can include control functionalities. These controlfunctionalities can be based on, for example, variable opticalattenuators. The control functionalities can be integrated with thecombiner via associated microprocessor(s).

Referring to FIG. 1, an 8-way optiplex is shown. Two optical signals, abroadcast signal, and a multiplexed narrowcast signal can be introducedas inputs to the system. Both inputs may be carried to the system viaoptical signal carriers. The optical signal carriers may include, butare not limited to planar waveguides, single mode optical fibers, multimode optical fibers, and photonic optical fibers.

A broadcast optical input 500 is coupled to an optical tap coupler 501.The optical tap coupler 501 is coupled to both a broadcast monitorphotodiode 502 and a 1*N optical broadcast splitter 504. The broadcastoptical splitter 504 may be connected to the tap coupler 501 via opticalsignal carrier 515 and the broadcast monitor photodiode 502 may beconnected to the optical tap coupler 501 via optical signal carrier 525.The optical signal carriers described herein may comprise, but are notlimited to, a planar waveguide, single mode optical fiber, multi modeoptical fiber, and/or photonic optical fiber. The broadcast monitorphotodiode 502 is coupled to a broadcast signal monitor input of asignal processing unit 400 via a bus 503. The signal processing unit 400includes a digital signal processor and as microcontroller. The opticalbroadcast splitter 504 is coupled to the broadcast signal input terminalof N (where N≧2) three-port optical combiners 700 via N optical signalcarriers 505.

A multiplexed narrowcast optical input 600 can convey N (where N≧2)multiplexed narrowcast optical signals. The narrowcast optical input 600is coupled to an optical wavelength division demultiplexer 601 via aoptical signal carrier. The optical wavelength division demultiplexer601 is coupled to N optical tap couplers 603, via N optical signalcarriers 602. Each of the optical tap couplers 603 are coupled to both anarrowcast monitor photodiode 604, and the narrowcast signal inputterminal of an associated three-port optical combiner 700. The opticaltap couplers 603 may be connected to the narrowcast monitor photodiodes604 via optical signal carriers 650, and to the narrowcast signal inputterminal of the optical combiners 700 via optical signal carriers 607.The narrowcast monitor photodiodes 604 are coupled to the narrowcastsignal monitor input of the signal processing unit 400 via a bus 605.Each of the N three-port optical combiners 700 includes an opticalfilter device that has passbands that are specific to the broadcast andnarrowcast wavelengths used. The optical combiners 700 can be tuned togive the desired combined outputs 800. The N combined outputs 800 can becoupled to external devices (not shown).

A local display and test points module 410 is coupled to the signalprocessing unit 400. A communications interface 420 is also coupled tothe signal processing unit 400.

It can be readily appreciated that there are two inputs to the system,the broadcast input 500 and the N-way optically multiplexed narrowcastinput 600. As the broadcast input 500 passes through the optical tapcoupler 501, a small amount of the broadcast input signal is split offand directed towards the diagnostic photodiode 502. The diagnosticphotodiode 502 sends a function of the broadcast input signal to thesignal processing unit 400 via the bus 503. The remainder of thebroadcast input signal is split into N broadcast outputs by the opticalsplitter 504.

The N-way optically multiplexed narrowcast input 600 passes through anoptical demultiplexer 601, where it is separated into N demultiplexednarrowcast signals. Each of the demultiplexed narrowcast optical signalsthen passes through one of N tap couplers 603 which in-turn splits off asmall amount of the narrowest optical signal to a one of N diagnosticphotodiodes 604. Each diagnostic photodiode 604 conveys a signal that isa function of its input to the signal processing unit 400 via the bus605. The remainder of each demultiplexed narrowcast signal 607 isdirected to a one of the N optical combiners 700, each of whichoptically combines the split broadcast output with a one of N narrowcastoutputs. Each optical combiner 700 outputs a multicast optical signal800.

Referring to FIG. 2, an 8-way optiplex is shown with the addition ofoptical level controls for both broadcast and narrowcast signals. Abroadcast input 715 is coupled to a variable optical attenuator 590 viaan optical signal carrier. The variable optical attenuator 590, via abus 120, to a broadcast signal attenuation control output of a signalprocessing unit 701. The variable optical attenuator 590 is also coupledto a tap coupler 160.

The narrowcast input 600 is coupled to the optical demultiplexer 601from which N demultiplexed narrowcast optical signals (where N≧2) areeach coupled to a one of N variable optical attenuators 990 via opticalsignal carriers 545. A narrowcast signal attenuation control output ofthe signal processing unit 701 is also coupled to each of the variableoptical attenuators 990, via a bus 220. Each variable optical attenuator990 is coupled to one of N tap couplers 672.

This system utilizes the signal processing unit 701 to condition thebroadcast signal and the demultiplexed narrowcast signals which arecombined to form N (where N≧2) multicast outputs. Signal characteristicsof the broadcast input may be altered using the variable opticalattenuator 590, which is controlled via the bus 120 by the signalprocessing unit 701. Signal characteristics of each demultiplexednarrowcast signal may be altered using the variable optical attenuator990 serially connected to each demultiplexed narrowcast signal. Eachvariable optical attenuator 990 may be individually controlled, via thebus 220, by the signal processing unit 701

The inputs are an optical signal carrying broadcast content and anoptically multiplexed set of optical signals carrying narrowcastcontent. The broadcast optical signal passes through the variableoptical attenuator (VOA) 590 whose transmission can be controlled by alocal or remote microcontroller to set the overall broadcast opticalsignal power at the output ports of the optiplex, an optical tap coupler160 (BTC) that splits off a small amount of light (nominally 1%) anddirects it to the photodiode 502 (BMPD) that is used by themicrocontroller 701 to measure the broadcast optical signal power level,and a 1×N optical splitter 504 (BS) where N≧2. Although the figures showthese elements in a particular order, these elements can be arranged inother configurations to accomplish the same functions.

Each of the output legs of the broadcast splitter (BS) is directed to awideband optical combiner 700 (BN), whose two input ports pass certainoptical wavelength bands to the output port 800 with low attenuation.Although not shown, a finer level of control over the broadcast opticalsignal power at each optiplex output port may be attained by placing avariable optical attenuator, tap coupler, and diagnostic photodiode ineach output leg of the broadcast optical splitter prior to the widebandoptical combiner (BN).

The narrowcast input conveys a set of N (where N≧2) optical signals withdistinct wavelengths that have been optically multiplexed onto a singleoptical signal carrier that connects to the optiplex at the narrowcastinput port. The multiplexed set of narrowcast optical signals passesthrough the optical wavelength division demultiplexer that separates thesignals by wavelength. Each of the narrowcast optical signals thenpasses through a variable optical attenuator (VOA) that is controlled bya microcontroller and a tap coupler (TC) that splits a small amount ofoptical signal and directs it to a diagnostic photodiode (PD). Thephotodiode output and the variable optical attenuator allow themicrocontroller to adjust the power of the narrowcast signal relative tothe broadcast optical signal power to maintain a specified power ratiobetween the two optical signals. The adjustment of the relative opticalpower levels is desirable to optimize the communication performance at areceiver (not shown) since the broadcast and narrowcast content may betransported with different modulation formats. An optical signal emergesfrom each of the output parts, which signal is a wavelength divisionmultiplexed combination of the broadcast optical signal and one of thenarrowcast optical signals.

The invention can also be included in a kit. The kit can include some,or all, of the components that compose the invention. The kit can be anin-the-field retrofit kit to improve existing systems that are capableof incorporating the invention. The kit can include software, firmwareand/or hardware for carrying out the invention. The kit can also containinstructions for practicing the invention. Unless otherwise specified,the components, software, firmware, hardware and/or instructions of thekit can be the same as those used in the invention.

The invention can also utilize data processing methods that transformsignals from the communications interface 420 to adjust and/or controlthe optiplex. For example, the invention can be combined withinstrumentation to obtain state variable information to actuateinterconnected discrete hardware elements. For instance, the inventioncan include the use of a transient event analyzer to control therelative signal strengths.

The term approximately, as used herein, is defined as at least close toa given value (e.g., preferably within 10% of, more preferably within 1%of, and most preferably within 0.1% of). The term substantially, as usedherein, is defined as at least approaching a given state (e.g.,preferably within 10% of, more preferably within 1% of, and mostpreferably within 0.1% of). The term coupled, as used herein, is definedas connected, although not necessarily directly, and not necessarilymechanically. The term deploying, as used herein, is defined asdesigning, building, shipping, installing and/or operating. The termmeans, as used herein, is defined as hardware, firmware and/or softwarefor achieving a result. The term program or phrase computer program, asused herein, is defined as a sequence of instructions designed forexecution on a computer system. A program, or computer program, mayinclude a subroutine, a function, a procedure, an object method, anobject implementation, an executable application, an applet, a servlet,a source code, an object code, a shared library/dynamic load libraryand/or other sequence of instructions designed for execution on acomputer system. The terms including and/or having, as used herein, aredefined as comprising (i.e., open language). The terms a or an, as usedherein, are defined as one or more than one. The term another, as usedherein, is defined as at least a second or more.

The particular manufacturing process used for combining the componentsof the optiplex should be inexpensive and reproducible. Conveniently,the assembly of the optiplex can be carried out by using any opticalconnector joining method. It is preferred that the process be preciseand accurate. For the manufacturing operation, it is an advantage toemploy an automated technique.

However, the particular manufacturing process used for combining thecomponents of the optiplex is not essential to the invention as long asit provides the described functionality. Normally those who make or usethe invention will select the manufacturing process based upon toolingand energy requirements, the expected application requirements of thefinal product, and the demands of the overall manufacturing process.

The disclosed embodiments show a tap coupler as the structure forperforming the function of diverting a portion of a signal fordiagnosis, but the structure for diverting a portion of the signal canbe any other structure capable of performing the function of diverting aportion of a signal for diagnosis, including, by way of example abeamsplitter.

While not being limited to any particular performance indicator ordiagnostic identifier, preferred embodiments of the invention can beidentified one at a time by testing for the presence of stable and evenresponse between the output channels. The test for the presence ofstable and even response can be carried out without undueexperimentation by the use of a simple and conventional data recordationexperiment.

PRACTICAL APPLICATIONS OF THE INVENTION

A practical application of the invention that has value within thetechnological arts is to combine a fanned-out optical broadcast signal(e.g., mass market entertainment) with any one of severalwave-division-demultiplexed optical narrowcast signals (e.g.,bidirectional packets). The invention is useful in maintaining a desiredpower ratio between narrowcast and broadcast signals. There arevirtually innumerable uses for the invention, all of which need not bedetailed here.

ADVANTAGES OF THE INVENTION

A broadcast/narrowcast combiner, representing an embodiment of theinvention, can be cost effective and advantageous for at least thefollowing reasons. The invention permits a broadcast/narrowcast opticalsystem to be assembled with fewer connectors. The invention permits abroadcast/narrowcast optical system to be assembled within a muchsmaller space, thereby achieving optimum packaging density. Theintegrated diagnostics permit information from multiple output ports tobe collected simultaneously. The embedded photodiodes also eliminate theneed for an optical spectrum analyzer. The feedback from the diagnosticphotodiodes enables the microcontroller to control the various signalpower levels using variable optical attenuators. The variable opticalattenuators also give the network operator an automatic and/or remotecontrol capability. The invention enables the signals from both thenarrowcast and broadcast inputs to be regulated simultaneously. Theinvention reduces costs and improves efficiency compared to previousapproaches.

All the disclosed embodiments of the invention disclosed herein can bemade and used without undue experimentation in light of the disclosure.Although the best mode of carrying out the invention contemplated by theinventors is disclosed, practice of the invention is not limitedthereto. Accordingly, it will be appreciated by those skilled in the artthat the invention may be practiced otherwise than as specificallydescribed herein.

Further, the individual components need not be formed in the disclosedshapes, or combined in the disclosed configurations, but could beprovided in virtually any shapes, and/or combined in virtually anyconfiguration. Further, the individual components need not be fabricatedfrom the disclosed materials, but could be fabricated from virtually anysuitable materials. Further, variation may be made in the steps or inthe sequence of steps composing methods described herein.

Further, although the combiner described herein can be a separatemodule, it will be manifest that the combiner may be integrated into thesystem with which it is (they are) associated. Furthermore, all thedisclosed elements and features of each disclosed embodiment can becombined with, or substituted for, the disclosed elements and featuresof every other disclosed embodiment except where such elements orfeatures are mutually exclusive.

It will be manifest that various substitutions, modifications, additionsand/or rearrangements of the features of the invention may be madewithout deviating from the spirit and/or scope of the underlyinginventive concept. It is deemed that the spirit and/or scope of theunderlying inventive concept as defined by the appended claims and theirequivalents cover all such substitutions, modifications, additionsand/or rearrangements.

The appended claims are not to be interpreted as includingmeans-plus-function limitations, unless such a limitation is explicitlyrecited in a given claim using the phrase(s) “means for” and/or “stepfor.” Subgeneric embodiments of the invention are delineated by theappended independent claims and their equivalents. Specific embodimentsof the invention are differentiated by the appended dependent claims andtheir equivalents.

1. A method, comprising: demultiplexing a multiplexed narrowcast inputsignal into a first narrowcast signal and a second narrowcast signal;conveying said first narrowcast signal to a first optical combiner;conveying said second narrowcast signal to a second optical combiner;tapping into said first narrowcast signal; monitoring a firstcharacteristic of said first narrowcast signal; tapping into said secondnarrowcast signal; monitoring a second characteristic of said secondnarrowcast signal; tapping into a broadcast signal; monitoring a thirdcharacteristic of said broadcast signal; attenuating a power of saidbroadcast signal as a function of said third characteristic; combiningsaid broadcast signal with the first narrowcast signal using the firstoptical combiner to give a first combined optical port output; andcombining said broadcast signal with the second narrowcast signal usingthe second optical combiner to give a second combined optical portoutput.
 2. The method of claim 1, wherein demultiplexing saidmultiplexed narrowcast input signal into said first narrowcast signaland said second narrowcast signal includes demultiplexing using anoptical wavelength division demultiplexer.
 3. The method of claim 1,further comprising: adjusting a first power of said first narrowcastsignal as a function of said first characteristic; and adjusting asecond power of said second narrowcast signal as a function of saidsecond characteristic.
 4. An apparatus, comprising: a first opticalinput; an optical splitter connected to said first optical input; afirst optical waveguide connected to said optical splitter; a secondoptical waveguide connected to said optical splitter; a first opticalcombiner connected to said first optical waveguide, said first opticalcombiner giving a first combined optical port output; a second opticalcombiner connected to said second optical waveguide, said second opticalcombiner giving a second combined optical port output; a second opticalinput; an optical demultiplexer connected to said second optical input,the optical demultiplexer demultiplexing a multiplexed narrowcast inputsignal into a first narrowcast signal and a second narrowcast signal; athird optical waveguide connected to said optical demultiplexer; afourth optical waveguide connected to said optical demultiplexer; afirst tap coupler connected to said third optical waveguide and saidfirst optical combiner; a second tap coupler connected to said forthoptical waveguide and said second optical combiner; a first opticalsignal sensor coupled to both said first tap coupler and a signalprocessing unit; a second optical signal sensor coupled to both saidsecond tap coupler and said signal processing unit; a third tap couplerconnected between said first optical input and said optical splitter,wherein said first optical input is a broadcast input; a third opticalsignal sensor coupled to both said third tap coupler and said signalprocessing unit; and a variable optical attenuator coupled between saidbroadcast input and said third tap coupler.
 5. The apparatus of claim 4,further comprising said signal processing unit and a communicationinterface coupled to said signal processing unit.
 6. The apparatus ofclaim 4, wherein said demultiplexer includes an optical wavelengthdivision demultiplexer.